This leaves me wondering what would happen if you attached a coupling to a trumpet and ran the sound through an effects/feedback box. Why should electric guitars have all the fun?
Well,i remember a performance of Jorge Lima Barreto (Portuguese electronic/free jazz) playing with a saxophonist with 2 microphones, one normal and the other with a brutal delay. He would play on the normal microphone and sometimes he directed the instrument output to the delayed microphone and it sounded monumental. Not sure what musician he was, i think is Tomas Stanko, but not sure. The performance sounded like you went through a big storm. :D
I like the thought, but trumpets require a lot of energy to excite them (i.e. you have to blow a LOT of air into a horn just to get a note. Getting an instrument like that to feedback would require a pretty radical system.
The difference with electric guitars is that guitar pickups are relatively sensitive and then go through multiple stages of amplification, which makes the system ripe for feedback loops.
Some saxophone players have been known to generate feedback through on-board microphones. Strictly speaking, this isn't exciting the horn, but it does introduce feedback that's excited BY the instrument.
People do! But you have to sit there and buzz your lips to make a trumpet make sound, but for a guitar you just have to shake the strings. And the sound coming from the amp will do this shaking, completing the feedback loop. So it's mostly portable stringed instruments that get this treatment. There are some violin players that play with feedback effects. I hear Jon Rose is one but I am not familiar with his music. Folks like Jean Luc Ponty and Jerry Goodman make ample use of guitar pedal effects in their violin. And there's a YouTuber out there who plays with them on her harp.
